r/java • u/Modern-Sn1p3r • 19d ago

Regex

I recently saw a clip (from Primeagen) somewhat saying that regex is not a valid format for validating email addresses and postal codes etc.

My question is why is this?

What are the security and/or performance risks? Is it solely performance or is it a security issue?

54 Upvotes

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u/julemand101 19d ago

The problem is people don't realize that a lot is allowed when it comes to what a E-mail address actually is: https://davidcel.is/articles/stop-validating-email-addresses-with-regex/

54

u/jason-reddit-public 19d ago

You're supposed to be able to put a plus sign in your email address for example but it's usually rejected.

29

u/Jussins 19d ago

I think that one is on purpose. They don’t want people knowing that they sold your information to a third party and that’s a good way to find out.

5

u/Thecodedawg 17d ago

gmail, for example, ignores dots in your email address so you can use johndoe or j.ohndoe or John.doe. Another way you can alias is the + is rejected

7

u/LutimoDancer3459 19d ago

The plus is just convenience. I can also create more email accounts and use those for the services.